I'm not convinced that "If this was happening in London or the South East, it would be treated as a national scandal." We southerners have our fair share of poor rail services, some of which we even share with our friends in the north.
Services in the more populous parts tend to be more frequent, so one service cancelled should be less of a problem, and there tend to be multiple trains / crews on many of the services too so that a shortage of operational staff or working trains leads to just a thinning which is less noticed.
Comparing perhaps extremes. Where I was brought up - Petts Wood - I see the next South Eastern timetable has 2 trains an hour to Charing Cross, 2 to Cannon Street, and 2 to Victoria. Inbound, any cancellation or disruption simply results in catching the next train, perhaps to a different terminus. Outbound, I was very used to changing at London Bridge or getting a train to St Mary Cray and walking home from there. Where I live now, if the 07:53 isn't running the next train is 10:02 ... and it's the same physical train so the impact of a cancellation isn't just a few minutes - it's two hours, even the assuming that they've found someone to fix or drive the train. True, there's a train at 09:09, but what good is ending up in Westbury when I need to be in Swindon?
I will suggest that the mayors might like to take a leaf out of the books of so many of us and "defensive plan" our journeys where the are to a time-vital meeting. It makes sense to travel one train earlier than really needed, and for the most of us who have "office work" to do, there's a chance to grab a quick coffee in a cafe and use the wait time producivly. It may be that the is not an option for the VIPs if they are so important that they don't do office work, passing it off to minions.